What is the difference between intravenous and subcutaneous immunoglobulin?

Intravenous immunoglobulin (IVIG) has been in use since the 1970s and involves giving immunoglobulin straight into the circulation system by a needle in a vein. Quite large amounts of immunoglobulin can be given this way and for this reason, treatment is only needed every three weeks or so, with each treatment lasting between two and four hours. If you have side effects with IVIG it is usually because it is being given too quickly. Initially you would have treatment in hospital, but most people can be trained to have it at home.

Subcutaneous immunoglobulin (SCIG) has been developed more recently than IVIG, with new immunoglobulin preparations being produced extensively for subcutaneous use by 2005. In SCIG, immunoglobulin is delivered by a needle into the fatty tissues under the skin, where it enters the circulation slowly over a few days. There isn’t much room under the skin, so the dose of immunoglobulin given is smaller than with IVIG. For this reason, SCIG is usually given every week. Nearly everybody on SCIG learns how to have treatment at home, with each session lasting up to about two hours.